CH. I] MAGIC LANTERN WITH DIRECT CURRENT 29 



FIG. 13. SQUARE ENGLISH LANTERN SLIDE FULL SIZE. 



This figure shows the method of "spotting" or marking by the English 

 Photographic Club. That is, there are two marks on the upper front margin 

 of the slide. Two marks are necessary for square slides, while a single one 

 answers for oblong slides. 



The picture on the lantern slide is of a retouching frame to hold the slides 

 while being colored. 



in its spiral casing the image may be made perfectly sharp, provided 

 that the light is good and the objective also good. With an 

 imperfectly corrected objective the margins of the screen image are 

 liable to be lacking in sharpness although the middle may be good. 



It may be necessary to focus slightly for each individual slide, 

 but ordinarily if one slide is in perfect focus those following will 

 also give good images. 



If the screen distance is small (three to five meters ; 10 to 16 feet) 

 it may be necessary to focus slightly for each slide if the sharpest 



